This invention relates to a unit which is connectible to a cross-country vehicle and is adapted to cleam entangled areas, e.g. power lanes in forests, railroad embankments, road embankments, road ditches, cultivated land etc., and also to carry out pre-regeneration and other similar silviculture work.
The growth of thicket, shrub and other vegetation along roads, railroads, in power lanes and elsewhere constitutes a very serious problem, which more recently has also become an environmental problem. Initially, attempts were made to control undesired vegetation manually by means of special tools, e.g. brush saws and the like, but very soon it was found that these tools did not suffice to control the increasing degree of shrubbery with a reasonable and economically justifiable man power investment. Attempts have been made to find other ways of solving this problem, and these have resulted in the development of tree-weeding with arboricides, i.e. the killing of the vegetation by chemical poisonous preparations, which are spread from airplanes or by portable or mobile spray units over the areas requiring treatment.
Tree weeding by arboricides has proved very effective and economically profitable. Therefore, this has become the dominant method for controlling undesired vegetation and, to some extent, has impeded the development of other methods. As great as its advantages may be, however, the cleaning by chemical preparations cannot be utilized for the control of conifers, and more recently this chemical method, involving application of poisons to forests and cultivated land, has encountered heavy criticism. This criticism arises from the fact that the preparations and poisons at present in use, e.g. hormoslyr and amisol, have, in the opinion of many persons, detrimental effects on human beings as well as animals and may also have long-time effects, so far unknown, which are a direct danger to the environment. This argument is deemed to provide sufficient reason to forbid any use of hormoslyr, amisol and other similar poisons as cleaning agents, at least until these poisons are proved to have no such detrimental effects. In the event of a ban of such poisons as cleaning agents, the situation will be the same as before the introduction of the chemical treatment, because there exist at present no alternatives to the chemical method although several attempts have been made to produce an efficient cleaning machine, for example, by applying the same principles as for mowing-machines and lawn-mowers. These attempts, however, have not yielded any concrete results so far.